It would be nice if you had some pictures to compare, because trust me your mind can play some tricks on you. When I started losing my hair, the more I looked at it the worse I was convinced it was getting, and this was just over the course of a few months!
Hair loss can progress slowly for some time, then speed up, and also start fast but slow down. It is certainly possible that your hair loss just happened to accelerate during the time you took finasteride. I've read quite a bit of the studies out there, and I haven't seen much of anything that suggests finasteride can accelerate hair loss aside from maybe an initial shed.
Are you sure your hair loss is due to male pattern baldness? DHT is what causes follicles to shrink and produce thinner hair. Reducing DHT by roughly 65% should only impede hair loss. I can't imagine any possible way it could speed it up. It might not regrow your hair or even stop it, but if you hadn't taken it, it's certainly possible and even probable that your hair would be just as bad or worse than it is now. Even in men who still lose hair, it is still technically 'working' by slowing down loss, even though it's not the ideal or expected result.
Sorry I don't have any real easy answers. I would stay on finasteride, because anecdotally I've heard from a few people that they didn't have results until past 2 years. I would also take some good pictures right now. Next time after you get a hair cut, take a shower, dry your hair, comb it forward and take a picture. Do this every time you get a hair cut and compare the results. This is really the only way you can see what's really going on.
Best of luck man!